Composite piston



C. R. SHORT COMPOSITE PISTON July 3, 1928.

Filed Feb. 23, -197526 gwuenfo'o LAME; 510R? 61110: ctr- Patented July 3, 1928.

UNITED STATES 1,675,618 PATENT OFFICE.

CHARLES R. SHORT, F DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS RESEARCH CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE.

COM POSITE PISTON.

Application filed February 23, 1926. Serial No. 90,160.

This invcntimi relates to improvements in pistons for internal-combustion engines and particularly to pistons of the composite type which comprise in their construction two or more diiterent kinds of material.

It is among the objects of the invention to produce a rigid, light-weight piston. the skirt of which is made of sheet metal such as steel and whose head and wrist pin bosses are made of a lighter and better conducting material, such as aluminum. Further objects and advantages of the invention. will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment is illustrated.

In the drawings: Fig. 1 is a longitudinal sectional view of the piston, throughthe piston bosses.

Fig. 2 is a section taken along the lines 2--2 of Fig. 1.

Fig. 3 is a transverse section taken along the line 3-3 of Fig. 1.

Fig. 4 is a view in elevation of the skirt of the piston unattached to the head.

Referring to the drawings, the piston comprises a skirt member 20, preferably made of sheet steel rolled into cylindrical shape and butt-welded. One end of the piston skirt is drawn to form a circular flange 21 which extends inwardly toward the axis of said .skirt and merges into an outwardly flaring conical flange 22.

On diametrically opposite sides of the piston skirt and substantially midway between its ends, there are provided cup shaped depressions 23 and 24. The bottom portions of these depressions are parallel and equidistant from the axis of the skirt 40 member, said bottom portions being apertured in such a manner that tongues 25 are formed by the edges thereof.

The portions 23 and 24 support piston pin bosses 26 and 27. respectively. These bosses are made preferably of aluminum and are cast on the skirt member 20. the portions 23 and 24 being embedded respectively in the bosses 26 and 27. The outer surfaces of the bosses are substantially flush and conform to the outer cylindrical surface of the piston skirt member 20. p

In order to increase the rigidity of the skirt and boss structure and particularly to maintain the bosses in aligmnent. there is provided a bridging member 30, certain vious to the casting of the bosses 26 and 27,

so that when said bosses are cast on the skirt. they will also be cast on the member 30, which thus forms a rigid connection between said bosses. a

The piston head 40 is preferably of metal oi less specific gravity and of greater thermal conductivity than the skirt. For ex ample, the head may be made of aluminum and may be formed and united to the skirt by casting in the same operation which tor-ms the piston pin bosses and unites them to the skirt, or the bosses may be formed and united in a separate operation.

The flange-s 21 and 22 of the skirtform anchoring means by which the piston head is securely joined to the piston skirt. The flanges are so related that the joint will remain tight throughout the working ranges of temperatures of the engine.

The bridging element may, of course, be secured to the wrist pin bosses in any suitable manner, the casting method described above being deemed the most satisfactory.

While the form of embodiment of the invention as I herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A composite piston comprising a skirt member; a head cast on the skirt; wrist pin lugs also cast on said skirt; and means interposed between the lugs separate from said head for increasing their rigidity.

2.. A composite piston comprising a cylindrical, sheet metal skirt; a piston head: piston lugs cast on said skirt; and a'bridgmg member separate from said head having an end anchored to each of said piston lugs to support and hold the lugs rigid.

3. A composite piston comprising a cylin drical, sheet metal skirt; a piston head; piston lugs cast on said skirt; and a. sheet metal bridging member having an end emsaid cup formations bein; directly opposite and the apertures thereof having notehed edges; a piston head on said skirt; a piston wrist pin. lug east on each of the cup formations of the skirt so that this entire formation is embedded in the lug; and a bridgin; member engaging portions ot the skirt and having portion thereof embedded in the lugs to hold them rigid.

In testimony whereof I aflix my signature.

CHARLES R. SHORT. 

